#!/bin/bash - 
#===============================================================================
#
#          FILE:  ex10-8.sh
# 
#         USAGE:  ./ex10-8.sh 
# 
#   DESCRIPTION:  usage-message
# 
#       OPTIONS:  ---
#  REQUIREMENTS:  ---
#          BUGS:  ---
#         NOTES:  ---
#        AUTHOR: bucunzai (), freecityer@gmail.com
#       COMPANY: FreeCity
#       CREATED: 2011年02月09日 14时52分27秒 CST
#      REVISION:  ---
#===============================================================================

set -o nounset                              # Treat unset variables as an error

: ${1?"Usage: $0 parameter"}
# Script exits here if command-line parameter absent,
#+ with following error message.
#   scriptname.sh: 1: Usage: scriptname.sh parameter

echo "There two lines echo only if command-line parameter given."
echo "command-line parameter = \"$1\""

exit 0 # Will exit here only if command-line parameter present.
